Bleach fixing of photographic silver images



United States Patent OfiFice 3,241,966 Patented Mar. 22, 1966 3,241,966BLEACH FllXlNG F PHOTOGRAPH-lit} SILVER WAGES Max Heilrnann,Cologne-Flittard, Hanswilli von Brachel,

@oiogne-Snlz, and Hans Holtschmidt, Cologne-Stammhelm, Germany,assignors to Agfa Alitiengesellschaft, Leverlrusen, Germany, acorporation of Germany No Drawing. Filed .lune 9, 1961, Ser. No. 140,170Claims priority, application Germany, June 14, 1960,

3 Claims. ((11. 9660) This invention relates to a process for bleachfixing of photographic silver images as well as to a bleach fixing bath.

According to German Patent Specification No. 866,605 the bleach fixingof photographic silver images is achieved by means of a bleach fix bathcontaining in addition to the known fixing agents for silver halide, acomplex salt of trivalent iron with an organic acid of the followinggeneral formulae:

and

R R and R represent hydrocarbon radicals which may be substituted and Rmay also represent hydrogen, and in which R R and R represent bivalenthydrocarbon radicals which may again be substituted. Examples ofsuitable organic acids are ethylenediamine tetra-acetic acid,nitrilotriacetic acid, malonic acid, ethyl malonic acid, tartaric acid,malic acid, fumaric acid, diglycolic acid, ethyliminodipropionic acid,ethylene dithioglycolic acid and dithioglycolic acid. These bleach fixbaths are highly stable and are used, in particular, for the productionof multicoloured images by the colour development process. Nevertheless,these baths have the disadvantage that they do not always completelybleach out the silver images at the areas of highest density,

It is known from German patent specification No. 966,410 that it ispossible to improve the effectiveness of the aforementioned bleach fixbaths without affecting their stability by adding a polyethylene oxideand/ or a derivative thereof to them. For this purpose, water-solublepolyethylene oxides are used, for example, polyethylene oxides of thegeneral formulae:

(GHQ-0112.0):

moronrornoa h N(OHz.CHzO)zR s In these formulae, R represents a hydrogenatom or a substituted or unsubstituted alkyl, aryl, aralkyl, acyl, aroylor heterocyclic radical; R and R which may be the same or different,each represent a hydrogen atom, a substituted or unsubstituted alkyl,aryl, aralkyl, acyl, aroyl or heterocyclic radical or the group(CH .Cl-I.O) ,R wherein R is a hydrogen atom or a substituent suitable for theetherification or esterification of an OH group and x, y, 2: and n areintegers. Examples of water-soluble polyethylene oxides which increasethe bleaching capacity of bleach fix baths are polyethylene oxidesconsisting of from 10 to 120 mols of ethylene oxide; reaction productsof fatty alcohols, for example oleyl alcohol, with from 60 to 100 molsof ethylene oxide; reaction products of lauric acid with from 10 to 20mols of ethylene oxide; reaction products of trimethylol propane withethylene oxide, which have an average molecular weight of 4000; reactionproducts of ammonia with from 20 to 30 mols of ethylene oxide; andreaction products of dimethylamine with from 50 to mols of ethyleneoxide.

It has now been found that the effectiveness of the bleach fix baths canbe further improved, without affecting their stability, if apolyalkylene oxide is added to them in which some of the oxygen atomsare replaced by sulphur atoms. This class of substances may becharacterised by the following general formula:

wherein R, R, R and R' represent bivalent organic radicals With 210carbon atoms which may be substituted, in represents an integer from0-100, n and p an integer from 1-100, Y stands for a radical selectedfrom the group consisting of and mixtures thereof wherein R" stands fora lower aliphatic radical having 1-3 carbon atoms and X represents ahydrogen atom or an aliphatic radical which may be substituted forimproving the solubility of said compounds e.g. by hydroxyl, cyano,amino, carboxyl, sulfo, or a radical of an acid of phosphorus. X mayfurther stand for an acyl radical derived from an aliphatic monoordicarboxylic acid.

Aliphatic, aromatic or mixed aliphatic-aromatic thioethers have provedsuitable. Aliphatic thioethers which contain a plurality of thioethergroupings in the molecule are preferred, however, because of theirgreater effectiveness. Furthermore, some of the sulphur atoms may beoxidised to sulphine or sulphonyl groups or some of the sulphur atomsmay be treated with an alkylating agent to form sulphonium groups.

Examples of suitable thioethers are condensates of 6,5- and y,'-dihydroxyalkyl sulphides with polyalklyene glycols, particularly theco-condensates of thiodiglycol and its alkyl-substituted products withpolyethylene and/or polypropylene glycols, or the hydroxyethylationproducts and/or the propoxylation products of monoand polyvalentalcohols which contain OH groups or other oxygen atoms as solubilizinggroups. Derivatives of the aforementioned polythioethers can also beused with success, for example co-condensates of the aforementioned typewherein some of the sulphur atoms have been oxidized to form sulphoxideor sulphonyl groups or in which some of the sulphur atoms have beenconverted by alkylation agents into sulphonium groups, or in which theOH groups have been Wholly or partially esterified or etherified.

Some of these substances and a process for the production thereof aredescribed in United States Patent Specifications Nos. 2,484,369 and2,518,245 and in French Patent Specification 1,201,171.

Examples of such thioethers are:

(1) A condensation product containing 3.8% of sulphur, having amolecular weight of 1700 and which has been prepared from 1 mol of apolyethylene oxide having a molecular weight of 1130 and 1.27 mols ofthiodiglycol.

(2) A condensation product containing 3.8% of sulphur, having amolecular Weight of 1540 and which has been prepared from 1 mol of apolyethylene oxide having a molecular weight of 680 and 0.94 mol ofthiodiglycol.

(3) A condensation product containing 3.7% of sulphur, having amolecular weight of 740 and which has been prepared from 1 mol ofoctaethylene glycol and 0.54 mol of thiodiglycol.

(4) A condensation product as recited under heading 2 in which the OHgroups have been converted into the semi-ester with maleic anhydride.

(5) A condensation product as recited under heading 2 in which theOH-groups have been esterified with acetic acid.

(6) A condensation product having a molecular weight of 4000 and whichhas been prepared from mols of thiodiglycol and 1 mol of a polyethyleneoxide having a molecular weight of 1700, the terminal groups of thecondensation product being esterified with maleic anhydride.

(7) A condensation product having a molecular weight of 4000 andcontaining 10% of sulphur, 20% of which has been converted into themethosulphate with dimethyl sulphate, said condensation product havingbeen prepared from 10 mols of thiodiglycol and 1 mol of a polyethyleneoxide having a molecular weight of 1700.

(8) A condensation product having a molecular weight of 4000 andcontaining 10% of sulphur, 40% of which has been converted into thesulphoxide, said condensation product having been prepared from 10 molsof thiodiglycol and 1 mol of a polyethylene oxide having a molecularweight of 1700.

(9) A thioether having terminal butyl groups, a molecular weight ofapproximately 2400 and containing 3% of sulphur, the thioether havingbeen produced by the condensation of 1 mol of diethylene glycolmonobutyl ether with 3 mols of thiodiglycol and 0.5 mol of apolyethylene oxide of molecular weight 1750.

(10) A polyether thioether having a molecular weight of 3000 andcontaining 3.3% of sulphur, said polyether having been produced by theco-polymerisation of 0.03 mol of butane-1,4-diol, 2 mols of ethyleneoxide and 0.1 mol of ethylene sulphide.

(11) A polyether thioether having a molecular weight of approximately3500 and containing 9% of sulphur, said polyether thioether having beenproduced by the copolymerisation of 0.03 mol of butane-1,4-diol, 2 molsof ethylene oxide and 0.4 mol of ethylene sulphide.

(12) A condensation product having a molecular weight of 4000 and whichhas been produced from one mol of a polyethylene oxide of molecularweight 680 and 0.76 mol of thiodiglycol, the terminal OH groups in thecondensation product having been etherified by the addition ofacrylonitrile in the presence of an alkali.

(13) A thioether having terminal amino groups and which has beenproduced by the hydrogenation of the product recited under heading 12.

(14) Dithiodiglycol HOCH CH SSCH CH OH (15) A condensation productprepared from 0.94 mol of thiodiglycol and 1 mol of polyethylene oxidehaving a molecular weight of 680, the terminal OH-groups of which beingetherified with acrylonitrile and the nitrile groups saponified to formterminal B-carboxyethyl-groups.

(16) A condensation product being produced from 10 mols of[3,,B-dimethyl-thioglycol and 1 mol of polyethylene oxide having amolecular weight of 1700, the terminal OH- groups of which are reactedwith butane sultone to form terminal sulfobutyl groups.

(17) A condensation product prepared from 10 mols of thiodiglycol and 1mol of polyethylene oxide with a molecular weight of 1700, the terminalOH-groups of which being transformed with thionylchloride into thecorresponding chloride which is reacted with triethylphosphite to formterminal phosphoric acid groups.

(18) A condensation product prepared from 10 mols of thiodiglycol and 1mol of a co-polymerisate of 1 mol of propylene oxide and 9 mols ofpolyethylene oxide having a molecular weight of 1700.

19) A condensation product having a molecular weight of 5200 and beingprepared from 1 mol of oxethylated TABLE 1 Processing of the film with aDensity behind a bleach fix bath: blue filter Without polyethylene oxide2.70 With 0.1 g. polyethylene oxide 2.35 With 0.5 g. polyethylene oxide2.20 With 1.0 g. polyethylene oxide 2.15 With 2.5 g. polyethylene oxide2.10

The difference of 0.6 between the maximum and minimum values of thedensities behind a blue filter represents a measure of the unbleachedresidual image of the field in question of a photometric test wedgeprocessed with a bleach fix bath without an additive.

From Table 1 it can be seen that an addition of at least 1 g. ofpolyethylene oxide is necessary in order to permit bleaching of theresidual image.

Table 2 shows the corresponding density values which were obtained in aseries of experiments with polyethylene oxides with and Without sulphur.The amount of polythioether being added was always 0.01 g. per liter ofbleach fix bath.

It is readily apparent from Table 2 that the same bleaching effect isobtained with a considerably smaller quantity of polyethylene oxidecontaining sulphur than in the case of the polyethylene oxides whichcontain no sulphur.

TABLE 2 Processing of the film with Density behind a a bleach fix bath:blue filter Without additive 2.7 With 1 g. polyethylene oxide 2.15 With0.01 g. of condensation:

Product No. 1 2.08 Product No. 2 2.2 Product No. 3 2.10 Product No. 42.15 Product No. 5 2.30 Product No. 6 2.13 Product No. 7 2.16 ProductNo. 8 2.25 Product No. 9 2.15 Product No. 10 2.15 Product No. 11 2.05Product No. 12 2.14 Product No. 13 2.15

Example 1 A photometric test wedge is exposed on an ordinary commercialtwo-layer negative colour film. The film is then developed at 18 C. forfive minutes in a colour developer of the following composition:

2.75 g. diethyl-p-phenylenediamine sulphate 1.2 g. hydroxylamine sulfate2 g. sodium sulphite (anhydrous) 2 g. sodium hexametaphosphate g.potassium carbonate 2 g. potassium bromide The film is then washed for15 minutes in running water, bleached and fixed in a bath of thefollowing composition:

40 g. of the sodium salt of the iron (III) complex of ethylenediaminetetra-acetic acid 9 g. of the tetrasodium salt of ethylenediaminetetra-acetic acid containing about 30% active ethylenediaminetetra-acetic acid (Trilon B of the BASF) 3.78 g. of free ethylenediaminetetra-acetic acid g. of sodium sulphite 200 g. of crystalline sodiumthiosulphate Water to make up to 1 litre If 0.0 1 g. of a condensate ofmolecular weight 1700 and containing 3.8% of sulphur and which has beenprepared from 1.27 mols of thiodiglycol and 1 mol of a polyethyleneoxide of molecular weight 1130 is added to this bleach fix bath perlitre, a film is obtained after 8 minutes which is free from anyresidual image.

If this additive is omitted, then a film which displays a considerableresidual image is obtained after the bleach fix.

Example 2 An ordinary commercial hard grade colour paper is exposedbehind a blue colour separation wedge and de veloped in the colourdeveloper employed in Example 1. The sample is then treated for 5minutes in a stop fix bath which has been prepared by dissolving 5 g. ofanhydrous sodium acetate, 10 g. of sodium bisulphate and 120 g. ofanhydrous sodium thiosulphate in 600 ml. of water and making up to 1liter with water. The pH value of the bath is 6.0.

The sample is passed into the bleach fix bath employed in Example 1without intermediate washing. If 1.0 g. of a condensate of molecularweight 1700 and containing 3.8% of sulphur and which has been preparedfrom 1.27 mols of thiodiglycol and 1 mol of a polyethylene oxide ofmolecular weight 1130 is added to the bleach fix bath a perfectlybleached yellow wedge is obtained after 8 minutes.

If 1.0 g. of a sulphur-free polyethylene oxide, for ex ample an additionproduct of 1 mol of ammonia and from to mols of ethylene oxide is addedinstead of the polyethylene thioether containing sulphur, the yellowwedge still displays considerable remains of the silver image after areaction time of 12 minutes.

Having thus described our invention we now state that we believe ourinvention to be capable of numerous variations. For example anywater-soluble thiosulphates may be used as fixing agents such as alkalithiosulphates or ammonium thiosulphate. The bleach fixing bath maycontain as stabilising agents any water-soluble sulfite, bisulfite ormetasulfite. Furthermore the bleach fixing bath may have an additionalcontent of water-soluble iodides as described in copending applicationSer. No. 95,735, filed March 14, 1961, by Bernard Morcher, Karl Frankand Max Heilmann.

Moreover it is clear to those skilled in the art that the photographicmaterial which shall be treated by the bleach fixing bath according tothe invention may be developed by means of any developer compositionknown per se.

The pH-value of the bleach fixing bath according to the invention mayrange approximately from 5 to 8.

As to the amounts of the sulphur containing polyalkylene-oxides beingadded to the bleach fixing bath according to the invention it isself-evident that smaller amounts than 0.01 g./l. of the bleach fixingbath are less eifective. Higher amounts may be added. The upper limit ofthe amount to be added is given by the solubility of said compounds,which depends on the molecular weight, the content of water-solubilizinggroups and so on.

We claim:

1. In a process for the bleaching and fixing of a photo graphic silverhalide emulsion which comprises subjecting the said emulsion totreatment with a fixing-bleaching composition comprising (a) aconventional bleaching agent of the group consisting of complex salts oftrivalent iron and an acid of the group consisting of polycarboxylicacids and nitrogen-containing polycarboxylic acids, and

6 (b) a conventional fixing agent consisting of a watersoluble salt ofthiosulfuric acid,

the improvement of subjecting the said emulsion to treatment with afixing-bleach composition which contains in dissolved form, in additionto the two foregoing conventional ingredients, at least 0.01 gram perliter of a sub!- stance of the group consisting of polyalkylene oxideshaving the formula:

wherein R, R, R" and R' are each a radical of the group consisting ofalkylene radicals having up to 10 carbon atoms and phenylene, m is aninteger from 0 to 100, n and p are each an integer from 1 to 100, Y is aradical of the group consisting of in which R"" is a lower aliphaticradical having up to 3 carbon atoms and X is a radical of the groupconsisting of (I) hydrogen, (II) alkyl containing up to 10 carbon atoms,(III) alkyl containing up to 10 carbon atoms and containing asubstituent of the group consisting of cyano, amino, carboxyl, sulfo andradicals derived from acids of phosphorous, (IV) aryl, (V) aryl radicalscontaining a substitutent of the group consisting of amino, carboxyl,sulfo and radicals derived from acids of phosphorus, and (VI) acylradicals of aliphatic monocarboxylic acids and aliphatic dicarboxylicacids, and mixtures thereof.

2. A bleaching and fixing composition for treating photographic silverhalide emulsions comprising (a) a conventional bleaching agent of thegroup consisting of complex salts of trivalent iron and an acid of thegroup consisting of polycarboxylic acids and nitrogen-containingpolycarboxylic acids, (b) a conventional fixing agent consisting of awatersoluble salt of thiosulfuric acid, and (c) in dissolved form atleast 0.1 gram per liter of a substance of the group consisting ofpolyalkylene oxides having the formula:

wherein R, R, R" and R are each a radical of the group consisting ofalkylene radicals having up to 10 carbon atoms and phenylene, m is aninteger from 0 to 100, n and p are each an integer from 1 to 100, Y is aradical of the group consisting of in which R"" is a lower aliphaticradical having up to 3 carbon atoms and X is a radical of the groupconsisting of (I) hydrogen, (II) alkyl containing up to 10 carbon atomsand (III) alkyl containing up to 10 carbon atoms and containing asubstituent of the group consisting of cyano, amino, carboxyl, sulfo andradicals derived from acids of phosphorus, (IV) aryl, (V) aryl radicalscontaining a substituent of the group consisting of aminq, carboxyl,sulfo and radicals derived from acids of phosphorus, and (VI) acylradicals of aliphatic monocarboxylic acids and aliphatic dicarboxylicacids, and mixtures thereof.

3. A bleaching and fixing composition for the treatment of photographicsilver halide emulsions comprising an aqueous solution containing thefollowing substances in approximately the quantities specified per literof solution:

(i) 40 grams of the sodium salt of the ferric complex ofethylenediaminetetraacetic acid,

(ii) 9 grams of the tetrasodi-um salt of ethylenediaminetetraacetic acidcontaining approximately 30% by weight of activeethylenediaminetetraacetic acid,

8,241,966 7 8 (iii) 3.78 grams of ethylenediaminetetraacetic acid,References Cited by the Examiner (iv) 10 grams of anhydrous sodiumsulfite, (v) 200 grams of sodium thiosulfate pentahydrate, and FOREIGNPATENTS (vi) 001 gram of condensation product having a mo- 54510838/1957 Canadalecular Weight of 1700 and containing 3.8% by 5 866,6052/1953 Germany' weight of sulfur that was prepared from thiodiglycol966,410 8/1957' Germanyand polyethylene oxide having a molecular weightof 1300 in the proportions of 1.27 mols of thiodiglycol NORMAN TORCHINPfimm'y Examine'l' per mol of the polyethylene oxide. HAROLD N.BURSTEIN, Examiner.

1. IN A PROCESS FOR THE BLEACHING AND FIXING OF A PHOTOGRAPHIC SILVERHALIDE EMULSION WHICH COMPRISES SUBJECTING THE SAID EMULSION TOTREATMENT WITH A FIXING-BLEACHING COMPOSITION COMPRISING (A) ACONVENTIONAL BLEACHING AGENT OF THE GROUP CONSISTING OF COMPLEX SALTS OFTRIVALENT IRON AND AN ACID OF THE GROUP CONSISTING OF POLYCARBOXYLICACIDS AND NITROGEN-CONTAINING POLYCARBOXYLIC ACIDS, AND (B) ACONVENTIONAL FIXING AGENT CONSISTING OF A WATERSOLUBLE SALT OFTHIOSULFURIC ACID, THE IMPROVEMENT OF SUBJECTING THE SAID EMULSION TOTREATMENT WITH A FIXING-BLEACH COMPOSITION WHICH CONTAINS IN DISSOLVEDFORM, IN ADDITION TO THE TWO FOREGOING CONVENTIONAL INGREDIENTS, ATLEAST 0.01 GRAM PER LITER OF A SUBSTANCE OF THE GROUP CONSISTING OFPOLYALKYLENE OXIDES HAVING THE FORMULA: